STOCKHOLM (AP).- Swedish prosecutors suspect three men arrested in an anti-terror sting this month of plotting to kill an artist who depicted the Prophet Muhammad as a dog, a newspaper reported Wednesday.

Citing classified material from the investigation, newspaper Metro said the target of the plot in the west coast city of Goteborg was Lars Vilks, who lives under police protection due to death threats over his drawing of Muhammad in 2007.

Authorities have remained tightlipped about the case and prosecutor Agnetha Hilding Qvarnstrom declined to comment on the report.

Vilks told The Associated Press he had not been given any details about the plot and didn't know whether he was the target. But he said Swedish authorities had advised him to cancel a planned visit Friday to a book fair in Goteborg because of it.

An art gallery celebrating the inauguration of an exhibition was evacuated in connection with the arrests on Sept. 10, sending jitters through Sweden on the eve of the 10-year-anniversary of the 9/11 terror attacks in the U.S.

Police arrested four men, originally from Somalia and Iraq, and initially suspected them of plotting a terror attack. Those suspicions were later dropped and three of them are now being held on preliminary charges of conspiracy to commit murder. The fourth suspect was released by a court, citing insufficient evidence.

Metro said the classified evidence includes references to a pocket knife and telephone conversations between the suspects. One of them is also supposed to have visited the arts center to inquire about Vilks. Metro didn't disclose how it had obtained the material.

The artist had mentioned on his blog that he planned to visit the exhibition, which runs for two months, but he did not attend the opening ceremony.

Vilks told AP he still planned to visit the exhibition at some point but dropped plans to attend an event at a separate book festival Friday because of "the incident in Goteborg and the attention surrounding it."

The 65-year-old artist has faced numerous threats over his 2007 sketch, which rekindled a debate over free speech and Islam that had raged a year earlier after a Danish newspaper printed 12 cartoons of Muhammad. Images of the prophet, even favorable ones, are considered blasphemous by many Muslims.

A Pennsylvania woman earlier this year pleaded guilty in a plot to try to kill Vilks. Two brothers were convicted of trying to burn down Vilks' house last year in southern Sweden. Also in 2010, angry protesters shouting "God is great" in Arabic disrupted a university lecture by Vilks when he showed a film about Islam and homosexuality.